39 – If you shave your head, less hair will grow back OR better hair and thicker hair will grow.
Shaving the head does not change the rate of hair growth. Few weak follicles in sleeping phase may not grow back immediately but would sure come back in the next 4 months. New growing hair looks thicker due to an optical illusion. Anything that is short in height looks thick, stout or fatter. In fact this new hair is the same thickness as the old hair.